Method of brightening metals



Patented Feb. 16, 1937 UNITED STATES METHOD OF BRIGHTENING METALS David B. Stockton, Detroit, Mich., assignor to Udylite Company, Detroit, Mich, a corporation of Indiana No Drawing. Application May 13, 1935, Serial No. 21,276

16 Claims.

This invention relates to the method of brightening metals electronegative to iron and belonging to the second sub-group oi the second group of the periodic system as given on pages 522-3 in the 16th edition of Handbook of Chemistry and Physics by Hodgman and Lange. More specifically the invention is concerned with the brightening of cadmium.

e method set forth below is applicable to any of these metals for brightening its surface regardless of how the metal is formed, that is, electrodeposited, sprayed, rolled, cast, etc.

To brighten the surfaces of these metals it is proposed to subject the surface of the metal to the action of an aqueous solution of an oxy-acid of a pentavalent halogen such as chloric, bromic and iodic acids. More particularly the method comprises dipping any one of these metals in an aqueous solution of any one of these acids.

Although the method is generally applicable to all of these metals, the specific application of the method to cadmium for brightening the same will be set forth. Detailed data on the treatment of cadmium by dipping'the cadmium in solutions of each of these acids at room temperature, at different concentrations, and for a period of time ranging from 5 to 30 seconds is as follows:

Chloric acid (H0103) .3 Normal solutionTrace oi brightening at I 5-30 seconds .5 Normal solutionVery slight brightening at 5-15 seconds, slightly cloudy at 30 seconds .8 Normal solution-Very slight brightening at 4 seconds, whitening at 5-30 seconds Normal solution-Slight brightening at 3 seconds, whitening at 4-30 seconds Normal solutionSlight brightening at 2 seconds, whitening at 3-5 seconds, then rebrightens partially Normal solution-Whitens, then partially rebrightens at 10-20 seconds Normal solutionWhitens, then partially rebrightens at 10-20 seconds Normal solution--Whitens, then partially rebrightens at 10-20 seconds Bromic acid (HBrOz) .03 Normal solution-Trace of brightening at 5-30 seconds. Normal solution-Trace of brightening at 5, slight brightening at -30 seconds .1 Normal solution-Good brightening at 5, ex-

cellent brightening 15-30 seconds .2 Normal solution-Excellent brightening at 5-30 seconds .4 Normal solution-Excellent brightening at 5-30- seconds .6 Normal solution-Excellent brightening at 5-30 seconds .755 Normal solution-Excellent brightening at 5-30 seconds Iodic acid (H103) .2 Normal solution-Very slight brightening at 5-15 seconds, whitened at 30 seconds .4 Normal solution-Very slight brightening at 5-15 seconds, whitened at 30 seconds .6 Normal solution-Slight brightening at 5-15 seconds, whitened at 30 seconds .75 Normal solution-,Slight brightening at 5-15 seconds, whitened at 30 seconds 1.00 Normal solutionSlight brightening at 5-15 seconds, whitened at 30 seconds 1.25 Normal solution-Slight brightening at 5-15 seconds, whitened at 30 seconds 1.474 Normal solution-Slight brightening at 5-15 seconds, whitened at 80 seconds The iodic acid leaves a slightly yellowish cast on the surface, probably consisting of some iodine compound. This thin film can be easily removed by immersion in a dilute acid solution, such as 5% by volume hydrochloric acid or sulphuric acid, or in a sodium cyanide solution.

I claim:

1. J'he method of brightening metals electronegative to iron and belonging to the second subgroup of the second group of the periodic system comprising subjecting the surface of the metal to the action of a solution of an oxy-acid of a pentavalent halogen.

2. The method of brightening metals electronegative to iron and belonging to the second subgroup of the second group of the periodic system comprising dipping the metal in an aqueous solution of an oxy-acid of a pentavalent halogen for a period ranging from 5 to 30 seconds.

3.. The method of brightening cadmium comcomprising subjecting the surface of the cadmium metal in an aqueous solution of an oxy-acid or a-- -to the action of a solution of an oxy-acid of a.

pentavalent halogen for a period ranging from 5 to 30 seconds.

5. The method of brightening metals electronegative to iron and belonging to the second subgroup of the second group 01' the periodic system comprising subjecting the surface of the metal to the action of a solution of bromic acid.

6. The method of brightening metals electronegative to iron and belonging to the second subgroup of the second group of the periodic system comprising dipping the metal in an aqueous soluf tion of bromic acid.

within the limits of from .03 normal to .755 normal and for a period of time ranging from 5 to 30 seconds. v

9; The method of brightening cadmium coniprising dipping at room temperature the cadmium metal in an aqueous solution of bromic acid having a concentration ranging i'rom .03 normal to .755 normal and for a period of time from 5 to 30 seconds. 7

10. The method 01 brightening cadmium comprising dipping the cadmium metal in an aqueous solution of bromic acid having a concentration anywhere from .1 normal to .755 normal for a period of time from 5 to 30 seconds.

11. The method oi brightening cadmium comprising dipping at room temperature the cadmium metal in an aqueous solution of bromic acid having a concentration anywhere from .1 normal to .755 normal for a period of time from 5 to 30 seconds.

12. The method of brightening metals electronegative to iron and belonging to the second subgroup, of the second group of the periodic system comprising subjecting the surface of 'the metal to the action of a solution of chloric acid.

13. The method 01' brightening cadmium comprising dipping the cadmium metal in a solution of chloric acid having a concentration ranging from .3 normal to 2.5 normal and for a period of 5 to 30 seconds.

' 14. The method of brightening cadmium comprising dipping at room temperature the cadmium metal-in a solution of chloric acid having a concentration ranging from .3 normal to 2.5 normal and for a period of 5 to 30 seconds.

15. The method of brightening metals electronegative to iron and belonging to the second sub-group of the second group of the periodic system comprising subjecting the surface of the metal to the action of the solution 01' iodic acid.

16. The method of brightening cadmium comprising dipping the cadmium metal in an aqueous solution of iodic acid having a concentration ranging from .2 normal to 1.474 normal.

DAVID B. STOCK'IDN. 

